STATE COLLEGE — Penn State has one of the best quarterbacks in the country, enviable depth at running back and tight end and a talented, albeit inexperienced group of wide receivers.

How those players perform will depend on how quickly a young offensive line with only one starter returning comes together, makes the holes and keeps defenders at bay.

Only junior left tackle Donovan Smith has started with nine coming in 2012 and 11 last season. Three other starters and key reserve Garry Gilliam graduated and guard Miles Dieffenbach tore his ACL in the spring and isn't expected back until late in the season at the earliest. Junior Angelo Mangiro, the projected starter at center, has played in all 12 games each of the past two seasons at guard, but as a reserve. Guards Derek Dowrey and Brian Gaia are converted defensive tackles and redshirt freshmen right tackle Andrew Nelson missed all spring with a knee injury.

Despite all that, sophomore quarterback Christian Hackenberg has total confidence in the guys who will be protecting him.

"I'm not concerned at all," Hackenberg said at last Monday's media day. "I've worked with these guys every day all year, and I couldn't be more confident and more proud to have these guys around me and calling them my teammates."

One of those teammates will be protecting Hackenberg's blindside for a second straight year.

Smith goes into his third year as a starter with 20 starts under his belt. An honorable-mention All-Big Ten pick last fall, Smith knows that he'll be looked at to help lead his inexperienced linemates as they acclimate themselves to playing on Saturdays.

"I take it very seriously," Smith said. "It's definitely a different deal out on the field and in games then it is in practice especially in Beaver Stadium. I try to instill whatever I can in these guys and whatever they want to ask me I'm free and open to answering anything."

Questions will most likely be coming from two players who were defensive tackles last season.

Dowrey and Gaia, both sophomores, each played as reserves on the defensive line in 2013. Gaia played in all 12 games, while Dowrey appeared in eight contests. Both players were standout offensive linemen in high school and have been able to adjust to the guard position with the Nittany Lions.

"They've done pretty well," Smith said. "They've really made the transition easy and I'm looking forward to seeing what they can do this season."

Nelson was a standout on the scout team last fall, but Bill O'Brien's staff was able to redshirt him.

Part of that was a nagging knee injury that Nelson sustained. That wound up keeping him out of action in the spring, which has only increased Nelson's hunger to get on the field.

"It's been a while since I've actually played in a football game," said Nelson, who was a standout at Hershey High School. "I'm excited for this season to start and to be able to play again."

What will help the offensive line get better should come from within.

The Nittany Lions have three starters back along the defensive line and talented depth inside and on the edge. Coaching the O-linemen will be Herb Hand, who has 24 years of experience at the college level including the last four as Vanderbilt's offensive line coach under James Franklin.

"I do think the fact that we have a defensive line that we have a lot of confidence in is going to be helpful because iron sharpens iron," Franklin said. "The fact that they are going to be out there at practice every single day going against what we feel is a quality defensive line is going to allow us to see where we're at.

"I feel good that we've got a really experienced offensive line coach. And we do have some guys who have played a little bit."